Steering Column Energy Absorption via Plastic Beam Fracture
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Solution Overview
Problem
Existing adjustable steering columns for vehicles face challenges in precisely adjusting the breakaway force during a crash, leading to inefficient energy absorption and increased costs.
Innovation Solution
Incorporating a blocking element made of a plastic bar anchored in lateral recesses, which can be designed for specific breaking properties to control the breakaway force, allowing the actuating unit to move relative to the transmission device only when a predetermined force is exceeded, and utilizing bending wires for enhanced energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rivets are used to connect the coupling element to the actuating unit, then the connection is simple to manufacture, but the breakaway force cannot be precisely adjusted to requirements
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the plastic beam (width, height, length, wall thickness) and material parameters (plastic type, reinforcement additives) to precisely control the breakaway force. The plastic beam's cross-sectional dimensions and material composition are adjusted to achieve specific energy absorption requirements, transforming a fixed rivet connection into an adjustable energy absorption system.
Solution Approach 2:
The patent uses composite materials by combining plastic with reinforcement elements such as glass fibers, carbon fibers, or metal inserts within the plastic beam. This composite structure allows precise tuning of the breakaway force while maintaining manufacturing simplicity, as the reinforcement materials can be incorporated during injection molding to achieve desired mechanical properties without complex assembly steps.
2Strength
If the plastic beam is made stronger, then the breakaway force increases, but the energy absorption capability during normal operation may be impaired
Solution Approach 1:
The patent applies dynamics by designing the plastic beam to exhibit different mechanical behaviors under different loading conditions. During normal operation, the plastic beam remains elastic and blocks the retaining element, providing reliability. During a crash, the plastic beam yields and breaks at a predetermined force, enabling energy absorption. This dynamic response ensures both normal operation reliability and crash energy absorption capability.
Solution Approach 2:
The patent implements beforehand cushioning by pre-designing the plastic beam with controlled weakness points or specific geometric features that will fail at a predetermined force. This pre-engineered failure mode ensures that during a crash, the plastic beam will break to release the retaining element and enable energy absorption, while remaining strong enough to maintain the connection during normal operation.
3Loss of energy
If the connection is designed to break away easily, then energy absorption is improved, but the structural integrity during normal operation may be compromised
Solution Approach 1:
The patent applies local quality by creating a localized weak point in the plastic beam's structure, such as a reduced thickness section or a predefined fracture zone. This local modification allows the connection to break away easily at the specific location during a crash for energy absorption, while the rest of the plastic beam and the overall coupling structure maintain sufficient strength for normal operation. The local quality change enables differentiated mechanical properties in different regions of the same component.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables a more defined breakaway force and efficient energy absorption during a crash, reducing the risk of component damage and assembly complexity while maintaining normal operation functionality.
Implementation Method 1
the blocking element consists of a plastic beam that extends transversely across the elongated hole and is anchored in two opposing lateral recesses of the elongated hole walls
Implementation Method 2
the plastic beam can be made more or less strong and can also be made of different plastics with different fracture properties
Implementation Method 3
utilizing bending wires for enhanced energy absorption
Data Source
Figure 1~3
Figure 4
Figure 5~6
AI summary
An adjustable steering column (1) for a motor vehicle comprises an adjusting unit (3) for mounting a steering shaft (2) such that it rotates about a longitudinal axis (7), and a support unit (4) in which the adjusting unit (3) is mounted such that it can be axially moved in the direction of the longitudinal axis (7) of the steering shaft (2) by means of a motor-driven longitudinal-adjustment drive (8) arranged on the support unit (4), and also comprises a transmission device that is coupled to both the adjusting unit (3) and the longitudinal-adjustment drive (8), an energy absorption device (29) being provided, which absorbs energy in the event of the adjusting unit (3) moving in relation to the transmission device, a coupling device being provided, which is connected to the adjusting unit (3) and to the transmission device, and, in the event of a crash, in which a force exceeding a pre-determined value acts on the steering shaft (2) in the direction of the longitudinal axis (7), the connection of the coupling device to the adjusting unit (3) and/or the transmission device being interrupted such that a movement between the adjusting unit (3) and the transmission device is allowed. in order to provide an adjustable steering column which, in the event of a vehicle crash, breaks away with a defined breakaway force, the coupling device comprises a pin-type retaining element (33, 34, 42) which protrudes into a slotted hole (32), a blocking element (38, 40) being provided, which prevents the movement of the retaining element (33, 34) in the slotted hole (32) and, in the event of a crash, permits the movement of the retaining element (33, 34) in the slotted hole (32).